A bit of geology

The fundamental ingredients to produce karst processes are abundant water rich in CO2 and organic acids, and a favourable type of rock, but in order to have long and deep cave systems, these conditions are not sufficient.
Pores and fissures 
Carbonatic rocks, which are most favourable for karst process, are generally very compact rocks. The granules forming them are very densely packed, the mechanisms by which they were formed led to a primary porosity ( i.e. a percentage of voids) and  permeability (i.e. a percentage of interconnecting voids that allow the passage of water) of these rocks that are very low. They are practically almost impermeable (the primary porosity of a limestone generally varies from 1 to 20%; only reef limestones have a higher primary porosity). In these conditions, karst processes can act only on the surface of the rocks, creating surface karst forms, such as karren (furrows and small depressions created by the dissolution of the rock): water has no possibility of filtering underground which is an indispensable condition for the formation of caves deep underground.
In order to be affected by karst processes deep underground, a rock must be characterized by discontinuities, through which water can filter and begin to percolate underground. Discontinuities that are very useful for this purpose are bedding planes, which often characterize limestones (dolomites instead are often massive and do not have any stratifications). Bedding planes form during sediment deposition, however most discontinuities in carbonatic rocks are secondary, of a tectonic origin. In fact carbonatic rocks are very fragile and get fractured easily if they are subjected to mechanical stress. Bedding planes are initially horizontal, but subsequent tectonic deformations can incline and fold them in various ways.

Special reports

  • 11 June 2012

    Bats, facts and fiction

    In ancient Rome, bats were nailed to the door of the house as a protection from witches...

    16 April 2012

    Bats, The Lords of Darkness

    The UNEP Convention on Migratory Species and The Agreement on the Conservation of...

    7 January 2010

    Alps and Appennines

    The term orogeny was born from the Greek words...

  • 13 May 2013

    Small steps, great footprints

    Have you ever wondered how much space is taken up by an apple or a steak?...

    18 May 2009

    Sauropods

    40 meters long and 17 high, huge...

    10 November 2011

    Landslides

    When studying landslide phenomena, it is opportune to distinguish...

  • 28 August 2020

    The Earth seen from above: signs of fires

    This image was taken by the ASTER sensor installed on the NASA TERRA satellite platform. The image was taken on…

    15 July 2020

    Earth viewed from above

    Remote satellite sensing: what it is and what it is used for In the scientific field, the images produced by…

    30 April 2019

    Urban woods

    When walking along a tree-lined avenue in a crowded and traffic-congested city, wrapped up in our daily commitments, we do…

  • 11 June 2012

    Bats, facts and fiction

    In ancient Rome, bats were nailed to the door of the house as a protection from witches...

    16 April 2012

    Bats, The Lords of Darkness

    The UNEP Convention on Migratory Species and The Agreement on the Conservation of...

  • 7 January 2010

    Alps and Appennines

    The term orogeny was born from the Greek words...

    13 May 2013

    Small steps, great footprints

    Have you ever wondered how much space is taken up by an apple or a steak?...

  • 18 May 2009

    Sauropods

    40 meters long and 17 high, huge...

    10 November 2011

    Landslides

    When studying landslide phenomena, it is opportune to distinguish...

From the Multimedia section

Facts

  • 13 May 2011

    Amphibians in a cave

    Proteus is an amphibian of white-yellowish or light pink colour...

    Can you breathe in a cave?

    One of the most common beliefs is that in caves the air is often stuffy...

  • Ice in caves

    In high mountain or high latitude environments, many caves can contain ice deposits...

    A walk underground

    The longest caves in the world are in Kentucky, the caves of Mammoth...

  • 24 February 2011

    And in underground tunnels?

    There are groups of terrestrial animals that eat insects, worms and other invertebrates...

    13 May 2011

    The climate underground

    Going down deep in the Earth’s crust, the temperatures increase gradually...

  • Amphibians in a cave

    Proteus is an amphibian of white-yellowish or light pink colour...

  • Can you breathe in a cave?

    One of the most common beliefs is that in caves the air is often stuffy...

  • Ice in caves

    In high mountain or high latitude environments, many caves can contain ice deposits...